In the MCU, the Avengers have saved the world and half of all life in the universe. In Marvel Comics, they've performed as many daring feats, but over the course of their near sixty-year history, some of the individual of the team have been even darker than their own villains. In fact, some key Avengers are actually responsible for the creation of some of their greatest villains, like Ultron.
Many of the Avengers have grim pasts that from a certain point of view are as horrific as any of their villains. Some of them have committed acts of violence and betrayal during their tenure with the team that are arguably worse than anything any baddie has ever done to them. That even goes as far as outright murder, with one Avenger taking the life of another during the Civil War II crossover event.
Hank Pym
Hank Pym is one of the most complicated figures in Avengers history. A founding member, he has proven darker than some of their antagonists on several fronts. Perhaps the most important is the fact that he created Ultron, one of the most powerful villains in the Marvel Universe.
If Hank Pym had stopped there, it would have been enough, but he didn't. He proved himself a bad friend and teammate by physically striking his wife, The Wasp. He also kidnapped her and tried to force her to marry him after claiming Hank Pym had died and he was someone else.
Black Widow
It's no secret at all Black Widow has a lot of red in her ledger. One of the most important spies in the Marvel Universe, Black Widow started off as a rogue by attempting to steal secrets from Iron Man and Stark Industries. Before that, she trained with the Winter Soldier as one of Russia's foremost undercover agents.
Though she reformed and ed the Avengers, Black Widow claimed a lot of lives in her time as a spy. She's arguably killed as many or more people as some of the Avengers' greatest bad guys, and few if anyone knows how bloody her past really is.
Ms. Marvel
Some of the scariest Avengers in the team's history were truly Dark Avengers. Moonstone became Ms. Marvel during the Norman Osborn-led era of the team, and the former Thunderbolt proved herself as much a villain as she was a hero in her time in the costume.
Moonstone established how different a Ms. Marvel she was going to be right from the get-go when she killed Morgan le Fay, one of the most powerful magicians in the Marvel Universe. She also kills a group of armored car robbers instead of turning them in.
Ragnarok
Thor is one of the most powerful superheroes in the Marvel Universe, and his evil duplicate Ragnarok is one of the evilest. Ragnarok was a cyborg clone of Thor created by Tony Stark, Reed Richards, and Hank Pym to replace Thor on the Avengers during the Civil War crossover.
Ragnarok attacked his own teammates during the epic conflict over the Superhero Registration Act and went so far as to kill Goliath. He was eventually taken down by the combined power of Storm and Hercules.
The Hulk
The Hulk is a complicated figure, often not in control of his angry and aggressive actions. But on a few occasions, he has consciously been a terrifying and dangerous "hero". One such occasion was during the World War Hulk storyline when he led a devastating invasion of Earth.
The Hulk was seemingly justified, believing the Avengers to be responsible for the death of his wife and knowing they were for his exile on Sakaar. But his deliberate attack on his former friends and allies as well as innocent civilians made him a true villain for a time.
Doctor Strange
Doctor Strange is one of the Avengers, together with the Illuminati, who consigned the Hulk to outer space in the first place. It was one of his most brutal acts, even if he thought it was necessary after Hulk went on a rampage through Las Vegas. His cold, calculating approach to all things is also evident in Spider-Man: No Way Home.
Some of the most powerful variants of Doctor Strange throughout the Marvel comics multiverse have been dark disciples of Dormammu, and he also served as God Emperor Doom's right-hand man in the 2015 Secret Wars storyline.
Hyperion
Hyperion is a member of the Avengers who actually started out as a bad guy. He was a member of the Squadron Sinister from Earth-712. Though he would eventually be recast as a hero in the Squadron Supreme, his actions are in some ways as villainous as his enemies.
As part of the Squadron Supreme on Earth-712, he subjugated the entire population and took control of the United States government. On Earth-616, he has attacked Atlantis and in one storyline, even killed Namor in a public and brutal battle.
Hawkeye
Hawkeye is generally considered one of the nicest Avengers, but as fans have discovered in the MCU, he can be as brutal as some of the antagonists. However, his darkest act in Marvel Comics is without a doubt his unprovoked murder of Bruce Banner in the Civil War II storyline.
After being convinced the Hulk will go on a rampage and destroy the Avengers, Clint Barton takes preemptive action and kills Banner with a gamma-tipped arrow. Though he's eventually cleared of any charges, his disturbing act drove a wedge between him and Kate Bishop.
Scarlet Witch
The Scarlet Witch is one of the most famous Avengers and she's also one the scariest. The Scarlet Witch used her many extraordinary powers to utterly dismantle her own team in Avengers: Disassembled, including killing Hawkeye in an attack on New York City.
Wanda Maximoff wasn't done. She committed her most frightening act, arguably one of the darkest in Marvel Comics history, when she erased all but a handful of mutants from existence in House Of M, a seminal storyline where she attempted to alter reality to restore her twin sons to life.
Iron Man
As is the case in the MCU, Iron Man is a complex figure in Marvel Comics. For decades he was a traditional hero, but in recent years he's gained many more shades of gray. Iron Man splintered the Avengers by ing the Superhero Registration Act and taking the battle against Captain America and other former teammates to the streets of New York City.
He also created Ragnarok and set him against the Avengers. He pushed Peter Parker toward revealing his secret identity to the world, which had disastrous consequences including the erasure of Peter's marriage to Mary Jane, which has yet to be restored. When Peter Parker sided with Captain America, Iron Man kicked him out of Avengers Tower, leaving Spider-Man with nowhere to go.
